Wat Chedi Ngam
The hills around Sukhothai are home to several forest temples, a tradition that derives directly from the life of the Buddha. Not much of these once large and important temples remains aside from foundations and some dilapidated stupas, but following the road from Wat Saphan Hin southward and exploring the area can be interesting. Wat Chedi Ngam - "the temple of the beautiful stupa" - is one of these. It sits on a low hill, and there isn't much left of the temple except the chedi, which sits on a large square base.
You can also see the remains of a pond dug into the stone of the hill and the bases of the prayer hall as well as other structures.